Many people run into portage problems when there's a major version Perl update. (Yes we're working to improve this.)

There's a lot of advice floating around, some of it correct, some of it unnecessary, and some of it straightaway harmful or dangerous. So, if you have problems with updating Perl, please visit our wiki page for up-to-date information (including both easy advice and the background story):

!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict:

dev-lang/perl:0

(dev-lang/perl-5.24.1-r1:0/5.24::gentoo, ebuild scheduled for merge) pulled in by
=dev-lang/perl-5.24* required by (virtual/perl-Data-Dumper-2.160.0-r1:0/0::gentoo, ebuild scheduled for merge)
^ ^^^^^
(and 18 more with the same problem)

(dev-lang/perl-5.22.3_rc4:0/5.22::gentoo, installed) pulled in by
dev-lang/perl:0/5.22=[-build(-)] required by (dev-perl/File-BaseDir-0.30.0-r1:0/0::gentoo, installed)
^^^^^^^^
(and 40 more with the same problem)

NOTE: Use the '--verbose-conflicts' option to display parents omitted above

I've been with Gentoo for over a decade and I still have problems "parsing" error messages such as above and understanding precisely what I need to do.
Thank you for the link, I'm hoping it will allow me to quickly resume.

There used to be warnings on portage updates that you were possibly in for some issues, and you should update portage first. Could we have some warning that a problematic update is looming? Like am eselect news item or something that says this is coming and where to go for the officially approved procedure?

And how long did it take people to figure out that was what to do? There were at least three different "this is how I did it" solutions that all involved a lot of time remerging broken packages. Not what you want on a "stable" system. There shoudl be a standard operating procedure published for the upgrade by the time it hits stable, as there often is for things that break your system before it's fixed, like major compiler or glibc updates.

I'm not whining, we want the maintenance of a stable system to be pretty straightforward. Gentoo has gotten much better in that regard since I started back in whenever.

ehm, the problems with perl is that emerge -uDNav --with-bdeps y --backtrack 100 @world will fail whenever a major change happened to perl, especially if you've installed about a thousand perl-packages. some of them simply are guaranteed to stop being supported in new versions? I don't know. anyway, thanks for gentoo-perl-helpers!